This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present techniques. This description is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present techniques. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
Some processing technologies provide for the conversion of a high quality gas into longer-chain hydrocarbons. As used herein a “high quality gas” can be formed by purification and fractionation to form a narrow molecular weight material. For example, recovered raw natural gas may be separated from recovered crude oil and later processed for the removal of water, natural gas condensate, acid gases, and other contaminants, and then fractionated into different molecular weight components to produce the high quality gas. The purification and fractionation may be done before the gas product is converted into the higher molecular weight hydrocarbons. This may be due in part to mainline transportation systems imposing restrictions on the make-up of the hydrocarbons before entry into additional processing units, pipelines facilities, or storage.
The technologies for the process of converting the high quality gas into the higher molecular weight hydrocarbons include relatively well-known and well-proven techniques that have been in development through the years. One example of a process that can convert a gas product into higher molecular weight hydrocarbons may include the Cyclar™ process from UOP. The Cyclar™ process is a non-integrated chemical production facility that converts liquefied petroleum gas (LPG) directly into a liquid, aromatic product. Particularly, the Cyclar™ process provides a process for upgrading lower value propane and butane (C3/C4 hydrocarbons) into a higher value, liquid aromatic concentrate (benzene, toluene, xylene, or “BTX”) that may be used as feedstock to an aromatics complex. The process may be typically operated at temperatures higher than 800° F. (425° C.). Another process is the Choudhary process, which also converts a percentage of methane, along with the C3/C4 hydrocarbons, to yield up to a 30% conversion of the methane along with a higher conversion rate of the C3/C4 hydrocarbons. See Journal of Natural Gas Chemistry 18 (2009) 260-272, Review: Energy-Efficient coaromatization of methane and propane, Jianjun Guo, Hui Lou, Xiaoming Zheng.
The Fischer-Tropsch process can also be used to convert hydrocarbons or natural gas into higher molecular weight hydrocarbons. The Fischer-Tropsch process is an exothermic conversion process including a collection of chemical reactions that can convert a mixture of carbon monoxide and hydrogen into liquid hydrocarbons. The more useful reactions produce mostly straight-chain alkanes, suitable for diesel fuel. Generally, the Fischer-Tropsch process is operated in the temperature range of 302° F. to 572° F. In this case, higher temperatures lead to faster reactions and higher conversion rates while favoring methane production. An increase in pressure in the process leads to higher conversion rates and also favors the formation of long-chained alkanes, both of which are desirable. Typical pressures can range from one to several tens of atmospheres.
Another process is the RZ™ Platforming process from UOP. The RZ™ Platforming process is designed to efficiently convert paraffins and naphthenes to aromatics with limited ring opening or cracking. Specifically, the RZ™ Platforming process utilizes a fixed bed system for the production of high yields of benzene toluene (BT) aromatics and hydrogen. Additionally, the Aromax® Process from Chevron Phillips selectively converts light paraffins and naphthenes to both hydrogen and aromatic products utilizing fixed-bed reforming equipment. The aforementioned process are just a few of the techniques used to convert high quality gas into aromatic products.
U.S. Patent Application Publication No. 2012/0036889 by Denton et al. discloses a methane conversion process. The process includes the conversion of a gaseous hydrocarbon feed, including methane, to an aromatic hydrocarbon. The methane conversion process is integrated with a liquefied natural gas (LNG) and/or pipeline gas process. In operation, the gaseous hydrocarbon stream is feed to a conversion zone with specified parameters to produce a gaseous effluent stream, including at least one aromatic compound, unreacted methane, and hydrogen.
U.S. Pat. No. 8,455,707 to Hershkowitz discloses a process for converting methane into acetylene and other higher hydrocarbons. The process includes a reverse-flow reactor system where first and second reactants are supplied in a first reactor bed such that both reactants serve to quench the reactor bed and to control combustion for thermal regeneration. See also U.S. Pat. No. 6,130,260 to Synfuels, which discloses converting methane into acetylene and then into liquid fuels.
U.S. Patent Application Publication No. 2007/0260098 by Iaccino et al. discloses the production of aromatic hydrocarbons from methane. The process includes a process to convert methane to aromatic hydrocarbons to produce first and second effluent streams. The hydrogen within the first effluent stream is reacted with an oxygen-containing species to produce a second effluent stream including a reduced hydrogen content.
U.S. Patent Application Publication No. 2009/0247804 by Sauer et al. discloses a method for converting methane to useful hydrocarbons. The process includes combining a methane/hydrogen fluid with a catalyst composition derived from an aluminum compound and a transition metal halide to produce higher molecular weight hydrocarbons.
Many other conversion process techniques exist for the production of aromatics from a high quality gas. However, the processes generally rely on an existing infrastructure, such as a chemical plant and purification systems. Accordingly, there is a need for an independent infrastructure process for the conversion of an unprocessed raw hydrocarbon gas to an aromatic product that may also incorporates other processing techniques including power generation and heat removal.